perf: Fix __percpu annotation

perf: Fix __percpu annotation

With bcecd5a529c1 ("percpu: repurpose __percpu tag as a named address
space qualifier") the normal compilers start caring about the __percpu
annotation, as such f67d1ffd841f ("perf/core: Detach 'struct
perf_cpu_pmu_context' and 'struct pmu' lifetimes") needs a fixup.

Fixes: f67d1ffd841f ("perf/core: Detach 'struct perf_cpu_pmu_context' and 'struct pmu' lifetimes")
Fixes: bcecd5a529c1 ("percpu: repurpose __percpu tag as a named address space qualifier")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: jirislaby@kernel.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>